FAA or faa - For appropriate action. As opposed to FYI or fyi, this one demands some kind of action on the part of the recipient, based on the circumstances. Back in the early '90s, we used faa interchangeably with For necessary action in office lingo. I'm retired now, and I don't know if faa is still in currency in office memos or if it has an entirely different meaning now for the younger set.